The present invention relates to a method for coating a quartz burner of a HID lamp with a UV-reflecting layer system.
For illumination purposes with high illuminance, high-intensity or high intensity-discharge (HID) lamps are used which have a plasma quartz burner as the lamp, the lamp being located inside a tubular jacket.
UV photons, which excite the atoms in the plasma to generate light in the visible range, play a central role in generating light in the plasma in the burner of HID lamps. With the known HID lamps, however, large UV photon fluxes leave the quartz burner unused. As such, the energy efficiency of the HID lamp is reduced.
The unused escaping of the UV photon fluxes could be reduced significantly if the quartz burner can be provided with a UV-reflecting layer system, which must be able to last for the entire service life of the lamp, however. Due to the aggressive plasma medium in the quartz burner and the high operating temperatures of the burner, this cannot be easily ensured, however.
UV-reflecting layer systems on different substrates are known from various publications, and they will be described individually hereinbelow. These known layer systems have not resulted in the desired success with quartz burners for HID lamps. One reason is that the coating step itself has proven difficult. Another reason is that no notable improvements in the energy balance were achieved.